1. Listeria Monitoring & Testing in RTE seafood plants
What to test, how to test, & how to take appropriate action

2. Goal of Listeria testing and monitoring testing program is to FIND Listeria
Listeria testing provides an opportunity to identify problems before they lead to finished product contamination, recalls, & regulatory actions

3. What to test? Raw materials Finished Products
Processing plant environment (all areas including raw, in-process, and finished product areas)
Food contact surfaces
Non-food contact surfaces

4. What to test for? Listeria monocytogenes Listeria species
The specific type (species) of Listeria that can cause human disease
Listeria species
Includes different species of Listeria, such as Listeria monocytogenes as well as Listeria innocua and others, which do not cause human disease

5. Why test for Listeria monocytogenes?
It is the specific type that causes human disease
Listeria monocytogenes specific testing is generally conducted when finished products are tested since only L. monocytogenes is considered an adulterant
Listeria testing may not always be a good indicator for presence of L. monocytogenes
Sometimes only 5-10% of Listeria species positive samples harbor L. monocytogenes
If finished product would be tested for Listeria spp. and would be found positive follow-up testing for L. monocytogenes would be required

6. Why test for Listeria species
More common than Listeria monocytogenes, thus more appropriate for routine monitoring
Test results may be available more rapidly than for Listeria monocytogenes
Testing may be cheaper than Listeria monocytogenes testing
Listeria species testing generally used for environmental samples

7. Raw material testing
May be important for raw materials to be used for cold smoking, which is a process that does not kill Listeria
May be used to test raw materials from new suppliers
May be used to continuously monitor raw materials from suppliers

8. Finished product testing
Finished product testing is NOT an essential part of a L. monocytogenes control program
Sometimes conducted at request of customers
Finished product testing requires specific definition of lots:
L. monocytogenes positive lots in commerce have to be recalled
In a test and hold program (which is recommended), L. monocytogenes positive lots have to be reprocessed or destroyed

9. Environmental Listeria testing
An essential part of each Listeria control program

10. Why environmental Listeria testing and monitoring?
Finished product contamination can most commonly be traced back to Listeria found in the processing environment
Finding of environmental samples positive for Listeria does not require product recall
Regulatory agencies are developing directives and guidance encouraging regular environmental Listeria testing

11. Goals of an environmental Listeria testing program
Identify problem areas harboring Listeria and locate contamination sources
Confirm effectiveness of problem-solving procedures

12. Critical considerations for environ-mental Listeria monitoring program
Design of environmental testing program
When to test (before start-up; mid-shift; end of shift?)
Where to test (product contact surfaces, cart wheels, drains?)
How often to test (weekly, monthly?)
Response to a positive sample

13. Environmental Listeria monitoring plan
Each environmental monitoring plan should be specific to the individual processing facility.
Listeria spp. testing is recommended for non-product and product contact surfaces

14. Where to test? Food contact surfaces Non-food contact surfaces
Food contact surface positives may have to be followed up with finished product testing
Non-food contact surfaces
Sites in coolers (floors, walls, cooler coils, condensate collectors etc.)
Tubs, conveyances, underneath tables
Floors, floor mats, walls, & drains in production areas

15. Testing of non-food contact surfaces
Initial weekly sampling is recommended for most wet areas where Listeria can grow
Some sampling sites should be constant (i.e., same site should be sampled regularly), but others can vary
Additional samples may need to be taken in proximity of positive samples

16. Where to test – the zone concept
Plant is divided into different zones; zones are defined based on relative potential for finished product contamination a site or area represents; sampling and corrections triggered by positive samples differ by zones.
Zone 1: Finished product contact surfaces
Zone 2: Non-food contact surfaces in finished product area
Zone 3: Product contact surfaces in raw product handling areas
Zone 4: Areas remote from finished product handling (e.g., non-product contact surfaces in the raw product handling areas)

17. When to test? Pre-op Mid-op Less likely to yield positive samples
More easy to interpret, will identify sanitation weaknesses
Mid-op
More likely to yield positive
Will provide information on spread of Listeria during processing

18. What to do with testing results
Review testing results every time results are reported
This should include review of last 4-8 sampling results to identify trends (e.g., site that has positives with intervening negatives
Take corrections on each positive sample and document action

19. What to do with testing results (cont’d)
Organize testing results in one location (folder, three-ring binder)
Include documentation of corrections in same location
Conduct regular (quarterly, yearly; depends on testing frequency & volume) review of testing results
Tabulate and evaluate long-term trends

20. Guidelines for corrective actions
Corrections based on positive samples need to be plant specific
Each positive sample should be followed up with additional investigations
Trend towards increased frequency of Listeria spp. needs to be investigated to determine reason and action needs to be taken to reduce frequency

21. Guidelines for corrective actions (cont’d)
Additional samples should be taken from environmental area that showed positive results
Additional positive samples after corrections need follow up with intensified cleaning and re-testing
Problems areas may have to be shut down temporarily
Consider if a test and hold program is needed

22. How is environmental testing performed?
Sponges are used to collect samples from selected environmental sites
Kits for sterile sample collection are available from testing laboratories
Hands-on training in proper sampling technique should be performed by professional
Environmental samples should represent constant areas (e.g., 2 x 2 ft)
Product contact surface samples should be collected from areas as large as possible

23. How is environmental testing performed? (cont’d)
After sample collection, sponge is deposited in sterile plastic bag and sealed
Sponges are sent to laboratory for testing

24. Example of Listeria Monitoring Plan

25. Pic 3#; mention that sample should be taken mid-op, and not pre-op on clean surface

26. Example – Medium sized plant pro-ducing hot & cold smoked products
Plant only tests environmental samples (non-product contact surfaces and product contact surfaces)
All testing is for Listeria spp.

27. Testing plan
Samples from 10 non-food contact surfaces are tested weekly; samples taken before production starts
6 sites in finished product area (1 floor sample near slicer; 1 sample from underneath tables used for product packaging, 2 employee contact surfaces, 1 floor drain, 1 sample from cart wheels
4 sites in raw material handling area (1 raw material cooler floor, 1 brining cooler floor, 1 floor drain, 1 underneath table used for raw material prep)

28. Testing plan (cont’d)
Samples from 5 product contact surfaces are tested weekly; samples taken at least 3 h after production started
1 sample from blade of slicing machine
1 sample from scale used to weigh product before packaging
1 sample from skinning machine conveyer belt
1 sample from trimming knife
1 sample from totes used to move cold-smoked products

29. Corrections – non-product contact surfaces
Raw material sites with positive results for 2 consecutive weeks will receive more stringent cleaning and sanitizer rotation until at least 3 of 4 consecutive tests are negative
Finished product area sites with a positive result will receive immediate attention and re-testing.
If re-test is positive line may be shut down (or go to test and hold procedure for finished products) and additional cleaning and sanitizing, including line disassembly will be implemented until three consecutive daily samples are negative.

30. Corrections – product contact surfaces
Sites with a positive result will receive immediate intensified cleaning and sanitizing, as well as daily sampling. If 2 consecutive samples are positive the area is shut down and extensive sanitation procedures are implemented. Swabs are taken before start-up and at two-hour intervals until 3 consecutive negative samples demonstrate that the contamination source has been eliminated; at that point routine testing can be resumed.

31. Summary
Listeria testing plan may include raw and finished product testing
Environmental Listeria testing is necessary to control this pathogen
Testing plant needs to be developed individually for each operation
Positive testing results need to be followed up with corrections, which need to be documented